title: Autoantibodies to aberrantly glycosylated MUC1 in early stage breast cancer are associated with a better prognosis.
abstract: BACKGROUND
  Detection of serum biomarkers for early diagnosis of breast cancer remains an important goal. Changes in the structure of O-linked glycans occur in all breast cancers resulting in the expression of glycoproteins that are antigenically distinct. Indeed, the serum assay widely used for monitoring disease progression in breast cancer (CA15.3), detects a glycoprotein (MUC1), but elevated levels of the antigen cannot be detected in early stage patients. However, since the immune system acts to amplify the antigenic signal, antibodies can be detected in sera long before the antigen. We have exploited the change in O-glycosylation to measure autoantibody responses to cancer-associated glycoforms of MUC1 in sera from early stage breast cancer patients.
  
  
  METHODS
  We used a microarray platform of 60mer MUC1 glycopeptides, to confirm the presence of autoantibodies to cancer associated glycoforms of MUC1 in a proportion of early breast cancer patients (54/198). Five positive sera were selected for detailed definition of the reactive epitopes using on chip glycosylation technology and a panel of glycopeptides based on a single MUC1 tandem repeat carrying specific glycans at specific sites. Based on these results, larger amounts of an extended repertoire of defined MUC1 glycopeptides were synthesised, printed on microarrays, and screened with sera from a large cohort of breast cancer patients (n = 395), patients with benign breast disease (n = 108) and healthy controls (n = 99). All sera were collected in the 1970s and 1980s and complete clinical follow-up of breast cancer patients is available.
  
  
  RESULTS
  The presence and level of autoantibodies was significantly higher in the sera from cancer patients compared with the controls, and a highly significant correlation with age was observed. High levels of a subset of autoantibodies to the core3MUC1 (GlcNAcβ1-3GalNAc-MUC1) and STnMUC1 (NeuAcα2,6GalNAc-MUC1) glycoforms were significantly associated with reduced incidence and increased time to metastasis.
  
  
  CONCLUSIONS
  Autoantibodies to specific cancer associated glycoforms of MUC1 are found more frequently and at higher levels in early stage breast cancer patients than in women with benign breast disease or healthy women. Association of strong antibody response with reduced rate and delay in metastases suggests that autoantibodies can affect disease progression.
authors.affiliation: Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark. olablixt@sund.ku.dk
authors.forename: Ola
authors.initials: O
authors.lastname: Blixt
authors.forename: Deanna
authors.initials: D
authors.lastname: Bueti
authors.forename: Brian
authors.initials: B
authors.lastname: Burford
authors.forename: Diane
authors.initials: D
authors.lastname: Allen
authors.forename: Sylvain
authors.initials: S
authors.lastname: Julien
authors.forename: Michael
authors.initials: M
authors.lastname: Hollingsworth
authors.forename: Alex
authors.initials: A
authors.lastname: Gammerman
authors.forename: Ian
authors.initials: I
authors.lastname: Fentiman
authors.forename: Joyce
authors.initials: J
authors.lastname: Taylor-Papadimitriou
authors.forename: Joy M
authors.initials: JM
authors.lastname: Burchell
mesh_terms: D000368:Aged; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D014408:Biomarkers, Tumor / Q000097:blood* / Q000276:immunology; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000276:immunology* / Q000473:pathology; D015331:Cohort Studies; D000939:Epitopes / Q000276:immunology; D005260:Female; D006020:Glycopeptides / Q000276:immunology; D006801:Humans; D008875:Middle Aged; D018396:Mucin-1 / Q000276:immunology*; D011379:Prognosis
chemical_list: D001323:Autoantibodies; D014408:Biomarkers, Tumor; D000939:Epitopes; D006020:Glycopeptides; C060192:MUC1 protein, human; D018396:Mucin-1